The current bat designs are generally made either of metal, composites or some combination of the two. The bats are monolithic (single material) in the barrel region or are multiwall designs made up of multiple materials.
Current bat designs are designed to maximize rebound velocity and there are varying methods designers use to achieve the same. Recent changes have been implemented by the various governing bodies for bats (such as the NCAA) limiting rebound velocity (or performance) under the guise of safety. For college players, this new BBCOR (Batted-Ball-Coefficient-Of Restitution) requirement went into effect Jan. 1, 2011. The requirement for most high school players goes into effect Jan. 1, 2012. This new BBCOR standard replaced a BESR (Ball-Exit-Speed-Ratio) requirement that had been in place for many years.
The history of metal bats is significant and can be traced to the early 1970's when the aluminum bat was first developed and commercialized. The NCAA approved aluminum bats in 1974 and aluminum has been the dominant metal bat material for decades.
Aluminum has been so integral to bat development that aluminum engineers at Alcoa and Kaiser credit baseball bats with much of the driving force behind high strength alloy development. A summary of the basis for this relates to the physics of the bat-ball collision and although not detailed herein, the accepted “norm” is that if you make the bat impact region “thinner” the rebound velocity will increase. A graph of various materials is attached to this application as FIGS. 1 and 2.
As described herein, the new “performance limiting” standards (BBCOR and ABI-Accelerated-Break-In) relate to the present invention and related features and benefits. Aluminum bats have improved steadily over the years as a direct result of advances in alloys. Stronger alloys allow bat designers to “thin-out” the impact zone (without the bat denting) and have resulted in higher and higher performance. These higher strength alloys are generally more expensive so there was a direct correlation between high strength alloy bats, high cost and high performance results (i.e., more rebound velocity). However, as noted earlier, the new BBCOR requirement has severely hampered 40 years of “conventional innovation” (better alloys or creative and complex multi-wall construction) all aimed at more rebound (i.e., “hotter” bat) velocity.
Composite bats also are a part of the high performance bat market. The materials and lay-up designs can be manipulated to produce barrel sections that are “softer.” A peculiar aspect of composite bats is that as they “wear out,” or the various layers begin to delaminate for separate), the barrel region actually gets even softer, and thus the rebound velocity at impact actually improves. There is a point of diminishing returns, but players have been known to strategically “break-in” their composite bats to secure added initial performance. This practice lead to the NCAA to ban composite bats a few years back and now they have implemented an “ABI” procedure as part of the qualification process to try and eliminate composite designs that “change” (i.e., get softer through delamination) over time. This has hampered the advantage composite bats have/had over aluminum. Composite bats (and their materials) are more expensive than aluminum.
These composite bats also must meet the new BBCOR requirement which means that designers must use “more” of this expensive composite material to ensure the right stiffness for “BBCOR” and enough strength for “ABI.” This adds little value and appears to be a carry-over from the marketing benefit of composites.
Thus, in summary, current bats must use expensive aluminum alloys, available only in “wrought” raw material conditions, in attempts to obtain performance standards that used to be “strength and weight” driven. This high strength to weight ratio is called “specific strength” and whether it was aluminum, titanium or composites, this was the “preferred” choice and selection. The performance standard was also either rebound velocity or maybe a derivative called “finding a larger sweet spot” which also dealt with velocity.
Future “high-performance” bats need to find a new parameter besides rebound velocity (for safety) and are preferably made of less costly materials and processes, and further and deliver features and benefits not solely focused on materials and/or construction.